Enhancing Porosity and Permissiveness in Particle-based Hydrogel Biomaterials

Wednesday, April 30, 2025

2:30 PM-4:00 PM

BIOMED Seminar

Title:
Enhancing Porosity and Permissiveness in Particle-based Hydrogel Biomaterials To Support Dynamic Cellular Activities and Bioprinting Using Hydrogel Microfibers
    
Speaker:
Chris Highley, PhD
Assistant Professor
Departments of Biomedical Engineering and Chemical Engineering
School of Engineering and Applied Science
University of Virginia

Details:
Tissue engineering and regenerative medicine require biomaterials that support cellular proliferation, migration, and self-organization to develop functional tissue structures. Granular hydrogel materials have potential to address this need, as they have intrinsic permissive properties resulting from microporosity among component microparticles and, when not crosslinked to one another, the potential for individual microparticle grains to move under applied forces. While traditionally composed of spherical particles, the incorporation of hydrogel microfibers introduces enhanced properties unavailable in conventional systems.

This lecture explores how high-aspect-ratio microfibers (102 μm diameter × 100 μm length) create long-range interparticle interactions that generate novel material properties. When combined with spherical microparticles, these fibers enhance porosity in granular hydrogels, with pore size and continuity increasing proportionally to removable particle content. Fiber-mediated crosslinking stabilizes systems that would otherwise erode. These scaffolds successfully support cell proliferation in vitro and revascularization in vivo. As the sole component in granular hydrogels, microfibers create materials that, like traditional granular hydrogels, exhibit yield stress and transition between solid and liquid behaviors under different stresses. They also demonstrate exceptional extensibility and rapid stress relaxation (tens of seconds) controllable through formulation adjustments. In bioprinting applications, fiber entanglements stabilize printed filaments without requiring interfiber crosslinking.

These systems support dynamic cellular behaviors including spreading, proliferation, and multicellular network development. They also facilitate embedded printing, allowing channel formation through fugitive ink removal. Taken together, granular systems incorporating hydrogel microfibers present new opportunities for designing 3D biomaterials for applications where permissive properties are essential for cellular activity and physiological function development.

Biosketch:
Chris Highley, PhD, is an Assistant Professor in the Departments of Biomedical Engineering and Chemical Engineering at the University of Virginia. His laboratory works on developing technology for the fabrication of material and cellular systems to address biological and medical needs. A central aim of the lab’s work is advancing capabilities to build biological constructs that achieve design-based, functional outcomes through precise multiscale control of construct structure and composition. In part to achieve goals around biofabrication, Dr. Highley's lab maintains a focus on the development and application of dynamic biomaterials. These materials also have unique permissive properties that are applicable in addressing biomedical challenges that do not involve biofabrication, including non-invasive delivery of regenerative biomaterial systems.

Dr. Highley received his BSE in Biomedical Engineering at Duke University and his PhD in Biomedical Engineering at Carnegie Mellon University. He was a postdoctoral researcher at the University of Pennsylvania before beginning his independent career.

Contact Information

Carolyn Riley
cr63@drexel.edu